1. Field of the Invention
This invention relates to a polyamino-bis-imide resin, solutions thereof, cross-linked resins derived therefrom and laminated boards therefrom. More particularly, this invention relates to a polyamino-bis-imide resin which dissolves in ordinary organic solvents of low boiling points and, on curing, acquires outstanding thermal resistance, solutions thereof, cross-linked resins derived therefrom and laminated boards therefrom.
2. Description of Prior Art
Heretofore, polyamino-bis-maleimide resins such as, for example, a polyimide resin formed of N,N'-4,4'-diphenylmethane-bis-maleimide and 4,4'-diaminodiphenylmethane have found acceptance in the production of heat resistant adhesives and heat resistant laminates which are required to exhibit thermal resistance, dimensional stability, electric properties, etc. all at high levels (U.S. Pat. No. Re. 29,316). These polyamino-bis-maleimide resins, however, have the disadvantage that they are soluble only in special high-boiling point solvents such as, for example, expensive N-methyl-2-pyrrolidone (202.degree. C. of boiling point) and N,N-dimethylformamide (153.degree. C. of boiling point). Use of such a special high-boiling point solvent has proved undesirable because the solvent has adverse effects on work environment and also because it remains in a high concentration in the shaped article formed of the resin. Particularly when this special high-boiling point solvent is used in the production of heat resistant laminated board, in the course of application of a prepared resin solution, varnish exudes from the prepreg and the solvent persists in the laminated board, possibly with the result that adverse affects will be brought about on properties such as boiling water absorption and resistance to measling.
As a solution of this problem, there has been proposed an imide type prepolymer produced by the reaction of an epoxy resin soluble in ordinary low-boiling point organic solvents with a bisimide and a diamine (U.S. Pat. No. 4,346,206). This imide type prepolymer, however, has the disadvantage that it exhibits a lower glass transition point than a polyamino-bis-imide resin formed of a bisimide and a diamine because it incorporates the epoxy compound.
An object of this invention, therefore, is to provide a novel polyamino-bis-imide resin and cross-linked resins derived therefrom.
Another object of this invention is to provide a polyamino-bis-imide resin which dissolves in ordinary low-boiling point organic solvents and, on curing, acquires outstanding thermal resistance and to cross-linked resins derived therefrom.